Thursday, November 25, 2010

Parasites.

A couple of evenings back I watched an episode of QI, which often comes out with some interesting facts. This particular episode touched on something that’s been a fascination of mine for some years: parasites (and I don’t mean the human kind). Here’s the little darling they were talking about:

...

The Spotted Rose Snapper Fish, which lives off the coast of California, is oft victim to another freaky parasite. The Cymothoa exigua parasite, a type of crustacean, swims into the fish’s mouth and attaches itself at the base of the poor Snappers tongue. It leeches blood from its victim and as it grows, the tongue withers and dies due to lack of blood supply. Eventually when the tongue dies completely, either diminishing or falling off, the parasite then switches places with the stump and acts as a working replacement for the organ, allowing the fish to use it just like a normal tongue.

The parasite spends the rest of its life living off both the fish’s blood and bits of food that enter the fish’s mouth. The Cymothoa exigua is the only parasite known to effectively replace a body organ.

If any of you have read any of the interviews with me you’ll know that The Skinner and the ensuing Spatterjay books can all be traced back to one instance. I was loaned a book on helminthology (the study of parasitic worms) by a vet, and read through it with growing fascination. I think the thing that got me first was the sheer number of transformations in the lifecycles of various parasites when, before, the limit of my knowledge on such changes was egg-caterpillar-chrysalis-butterfly, and how some parasites actually change their host for their own benefit. Two of them stuck in my mind. One includes both ants and sheep in its life cycle. It interferes with the ant’s brain and makes it climb to the top of a stalk of grass and cling there, waiting for a grazing sheep. Another gets inside a snail to breed, but to protect itself, causes the snail to grow a thicker shell. Here, with Cymothoa exigua, are a few more.

This reading resulted in various short stories: The Thrake, The Gurnard, Out of the Leaflight, Choudapt, Spatterjay and Snairls. They then resulted in the novella no one can get hold of: The Parasite. Then I took two short stories, Spatterjay & Snairls, and on the basis of them wrote The Skinner. I definitely must read some more of this stuff.

Check out these beauties: http://en.wikipedia.org/wiki/Emerald_cockroach_wasp

"The wasp proceeds to chew off half of each of the roach's antennae. Researchers believe that the wasp chews off the antenna to replenish fluids or possibly to regulate the amount of venom because too much could kill and too little would let the victim recover before the larva has grown. The wasp, which is too small to carry the roach, then leads the victim to the wasp's burrow, by pulling one of the roach's antennae in a manner similar to a leash. Once they reach the burrow, the wasp lays a white egg, about 2 mm long, on the roach's abdomen. It then exits and proceeds to fill in the burrow entrance with pebbles, more to keep other predators out than to keep the roach in.

With its escape reflex disabled, the stung roach will simply rest in the burrow as the wasp's egg hatches after about three days. The hatched larva lives and feeds for 4–5 days on the roach, then chews its way into its abdomen and proceeds to live as an endoparasitoid. Over a period of eight days, the wasp larva consumes the roach's internal organs in an order which guarantees that the roach will stay alive, at least until the larva enters the pupal stage and forms a cocoon inside the roach's body. Eventually the fully grown wasp emerges from the roach's body to begin its adult life. Development is faster in the warm season."

It's there at the end of the link in that post. I think it's one of the ichneumon wasps (and there's 10s of thousands of them) which, of course, Alien was based on. However I'm not that great on taxonomy so won't commit myself on that.

"The Ichneumonidae have been and still are quite a taxonomic nightmare. About as diverse as the true weevils ( Curculionidae), there are numerous small, inconspicuous and hard-to-identify ichneumon wasps. The sheer diversity means that DNA sequence data is only available for a tiny fraction of the species, and that detailed cladistic studies require major-scale computing capacity."

"They then resulted in the novella no one can get hold of: The Parasite."

Never underestimate the power of online shopping! If someone is willing to pay US$75.85 for it, there's a 2nd-hand copy of The Parasite available here: http://www.abebooks.com/servlet/SearchResults?an=neal+asher&sts=t&tn=parasite&x=0&y=0

I can't tell you how much I love AbeBooks for finding obscure books :)